Concrete walls, and other concrete structures, traditionally have been made by building a form. The forms are usually made from plywood, wood, metal and other structural members. Unhardened (i.e., plastic) concrete is poured into the space defined by opposed spaced form members. Once the concrete hardens sufficiently, although not completely, the forms are removed leaving a concrete wall, or other concrete structure or structural member. The unprotected concrete wall is then exposed to the elements during the remainder of the curing process. The exposure of the concrete to the elements, especially temperature variations, makes the curing of the concrete, and the ultimate strength it can achieve, as unpredictable as the weather. Therefore concrete structures are typically overdesigned with significant safety factors to make up for the unknown variables and uncertainty of the curing process.
Historically concrete has been placed in forms made of plywood reinforced by different types of framing members. Concrete placed in conventional forms is exposed to the temperature and humidity of the environment thus making the curing, and therefore the strength, dependent upon these variable factors. Concrete has high thermal mass and since most concrete buildings are built using conventional forms, the concrete assumes the ambient temperature. Thus, although they have many advantages, concrete buildings have relatively poor energy efficiency.
Insulated concrete form systems are known in the prior art and typically are made from a plurality of modular form members. In order to assist in keeping the modular form members properly spaced when concrete is poured between the stacked form members, transverse tie members are used in order to prevent transverse displacement or rupture of the modular form members due to the hydrostatic pressure created by fluid and unhardened concrete contained therein. U.S. Pat. Nos. 5,497,592; 5,809,725; 6,668,503; 6,898,912 and 7,124,547 (the disclosures of which are all incorporated herein by reference) are exemplary of prior art modular insulated concrete form systems.
Insulated concrete forms reduce heat transmission and provide improved energy efficiency to the building in which they are used. However the insulated concrete forms of the prior art have multiple shortcomings.
Concrete is a relatively heavy material. When placed into a vertical form the pressure at the bottom of a form filled with concrete is measured by multiplying the height of the wall by 150 lbs per square foot. In other words when pouring a 10 feet tall wall, the pressure at the bottom of a form will be 1500 lbs/ft2. In addition, safety codes, and various concrete regulating bodies, demand that commercial forms be built to withstand approximately 2.5 times the static concrete pressure a form is actually intended to hold.
Conventional forms typically use aluminum or some type of plywood reinforced by a metal framing system. Opposed form members are held together by a plurality of metal ties that provide the form with the desired pressure rating. Conventional forms are designed to be strong, safe and durable to meet the challenges of any type construction, residential or commercial, low-rise or high-rise, walls, columns, piers or elevated slabs. While insulated concrete forms of the prior art provide relatively high energy efficiency, they lack the strength to withstand the relatively high fluid concrete pressures experienced by conventional concrete forms. Consequently, they are relegated mostly to residential construction or low-rise construction and find few applications in commercial construction.
In order to achieve relatively high energy efficiency, one must use insulated concrete forms made from foams with relatively high R values. However all types of foam have relatively low strength and structural properties. Therefore, insulated concrete forms of the prior art are relatively weak and cannot withstand the same high pressures experienced by conventional forms. Prior art insulated concrete forms have attempted to solve this problem by using higher density foams and/or by using a high number of ties between the foam panel members. However, such prior art insulated concrete form systems still suffer from several common problems.
First, in the construction of an exterior wall of a building, multiple insulated concrete form modules are stacked upon and placed adjacent to each other in order to construct the concrete form. In some insulated concrete form systems, the form spacers/interconnectors are placed in the joints between adjacent concrete form modules. Such form systems are not strong enough to build a form more than a few feet high. Concrete is then placed in the form and allowed to harden sufficiently before another course of insulating forms are added on top of the existing forms. Such systems result in cold joints between the various concrete layers necessary to form a floor-to-ceiling wall or a multi-story building. Cold joints in a concrete wall weaken the wall therefore requiring that the wall be thicker and/or use higher strength concrete than would otherwise be necessary with a wall that did not have cold joints. This generally limits current use of insulated concrete forms to buildings of a single story or two in height or to infill wall applications.
Second, the use of multiple form modules to form a wall, or other building structure, creates numerous joints between adjacent concrete form modules; i.e., between both horizontally adjacent form modules and vertically adjacent form modules. Such joints provide numerous opportunities for water from the concrete mix to leak out of the form. The proper amount of water and heat is necessary for concrete to harden to its maximum potential strength. Thus, the loss of water through leaky joints in adjacent form modules reduces the strength of the concrete.
Third, the use of multiple form modules to form a wall, or other building structure, creates numerous joints between adjacent concrete form modules; i.e., between both horizontally adjacent form modules and vertically adjacent form modules. The sum of all these joints makes the prior art insulated concrete forms inherently unstable and concrete blowouts are not uncommon. Since the wall forms are unstable, the use of additional forming materials, such as plywood, to stabilize the modular insulated concrete forms is required before concrete is poured. These additional materials are costly and time consuming to install. The multiple joints also provide numerous opportunities for water to seep into and through the concrete wall. Furthermore, some of the prior art wall spacer systems create holes in the insulated concrete forms through which water can seep, either in or out. Thus, the prior art modular insulated concrete forms do little, or nothing, to prevent water intrusion in the finished concrete wall.
Fourth, prior art modular insulated concrete form systems are difficult and time consuming to put together, particularly at a constructions site using unskilled labor.
Fifth, prior art modular insulated concrete form systems do little, or nothing, to produce a stronger concrete wall.
Sixth, prior art modular insulated concrete form systems do not meet the high pressure ratings that conventional concrete forms do.
Seventh, prior art modular insulated concrete form systems are designed to form walls and are not suitable for forming columns or piers or elevated concrete slabs.
Eighth, prior art modular insulated concrete form systems do not allow for forming of structural, load bearing high-rise construction
Ninth, prior art modular insulated concrete form systems only allow for one type of wall cladding to be applied, such as a directly applied finish system. To install all other wall claddings, additional systems have to be installed, sometimes at greater expense than even in the conventional concrete forming systems. Some prior art modular insulated concrete form systems do not allow for the use of other types of wall cladding systems.
It would therefore be desirable to provide an insulated concrete form system that is relatively easy to assemble is stronger and permits the construction of floor-to-ceiling high walls without joints in the form and without cold joints in the concrete. It would further be desirable to provide an insulated concrete form system that reduces or eliminates water leakage from a plastic concrete mix placed in the form that would thereby allow the concrete to retain the moisture necessary for its proper curing to achieve its maximum strength. It would also be desirable to provide an insulated concrete form system that produces relatively harder concrete. It would also be desirable to provide an insulated concrete form system that prevents, or reduces, water intrusion through the finished wall. It would further be desirable to provide an insulated concrete form system that specifically accommodates and economically integrates different types of finished wall and/or ceiling cladding systems for both interior and exterior applications. Also, it would be desirable to provide an insulated concrete form system that can withstand the fluid concrete pressures equivalent to those of conventional concrete forms. In addition it would be desirable to provide an insulated concrete form system that can be used to form concrete walls, columns, piers, elevated slabs, roof systems and other concrete structures.